Traditionally, in North America, the film used for packaging fluid milk or the like in flexible plastic pouches consists of a 76 microns (3 mil) mono-layer polyethylene film.
However, this standard film has some disadvantages which should be overcome. For example, the packaging operation requires a certain amount of electrical energy for the heat sealing operation due to the thickness of the film. To generate this heat electrical energy is dispensed. It is desirable to develop a process which could decrease the energy consumption in order to make the operation more economically feasible. Another problem involved with the sealing operation is that some of the hardware, such as the sealing element per se and the rubber and Teflon.TM. parts associated with the sealing jaws have a relatively short useful life, requiring frequent changes and again increasing the cost of producing milk pouches.
Yet another problem resulting from the packaging of liquids with a mono-layer polyethylene film is the amount of waste and machine downtime due to film roll changes and seal breaks. Packaging milk or other liquids with mono-layer polyethylene also involves the use of a narrow sealing window which renders the operation somewhat difficult. Finally, the seals obtained with this type of film pouches, often exhibits weakness which can cause fluid leakage.
Polymer film pouches made from a polyethylene film structure and used for packaging flowable materials such as milk, are known and examples of such are described in U.S. Pat. Nos. 5,288,531; 5,360,648; 5,364,486 and 5,508,051, all of which have issued to the Down Chemical Company.